Hydraulic acceleration integrator switch



W. B. M' LEAN Filed June 24, 1946 INVENTOR WILL/AM B. "CLEAN ATTORNEY HYDRAULIC ACCELERATION INTEGRATOR SWITCH July 15, 1952 FIG. I.

upper portion of cylinder l. "of rod l3 overlies a central aperture D in a mov- Patented July 15, 1952 HYDRAULIC ACCELERATION I SWITCH IN TE GRATOR William B. McLean, Washington, D. 0., assignor to the United States of America as represented by the Secretary of the Navy Application June 24, 1946, Serial Nb. 678,756 1 Claims. (01.200 52) (Granted under the act of March 3, -1883, as i This invention relates to acceleration integrators for establishing a time interval which is a function of the acceleration of the whole mechanism, and more particularly to a novel hydraulic acceleration integrator for this purpose.

An object of the invention is the provision of an acceleration integrator in which a movable weight responsive to the acceleration of the entire apparatus traverses an oil-filled chamber from which the oil is extruded through a series of orifices.

Another object is the provision of means for biasing the weight against gravity to enable a function of the acceleration to be integrated.

Another object is the provision of combined spring and solenoid-operated means for resetting the integrator.

These and other objects of the invention may be better understood by reference to the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of one form of the new integrator, showing the positions of the parts after operation of the integrator, and

Figs. 2 and 3 are sectional views on the lines 2--2 and 3-3, respectively, in Fig. 1.

The device as shown comprises a main cylinder l-Ia having its ends closed by a head 2 at one end and a head 3 at theopposite end, the latter head having a threaded integral nipple 4 extending centrally therefrom. Surrounding the nipple 4 and in threaded engagement therewith is'a cylindrical insulating member 5 having its inner wall threaded to receive a sleeve 6. The inner wall of the latter is threaded to receive a threaded plug 1 of insulating material which is moved vertically according tothe rotation given a shaft 8. having a square end 8a fitting intoa similarly shaped recess in the plug 1. A cap 9 maintains the alignment of shaft 8, and a knurled disk Ill facilitates the turning of shaft 8 by hand.

The cylindrical member 5 has an inner bore H aligned with the nipple portion 4, the latter, having a bearing l2, receives a rod 13. The'rod "13 has a head or enlargement [4 at its upper end and passes through and is united to a piston 15 near its lower end, as by a pin lib. The piston defines the bottom of a chamber A in the The extremity l6 able solenoid core I1 which is moved downward upon energization of a surrounding solenoid I8. The solenoid is adapted to be energized by the closure of a simple operating circuit such as G.

A cylinder 15 in the solenoid serves as a guide for the core I! and is held in alignment by a amended April 30, 1928; 3'70. 0. G. 757) shouldered ring 20, which joins the cylindrical sections I and la, and by a conical-ended, stationary'solenoid core 2| screwed into the head 2. The cylinder l9 has a cap Isa which, with the cylinder l9 and the upper end of movable-core ll, defines an annular chamber C around rod it when the parts are in their final positions as shown. At its'lower endportion, the core I! is reduced to form an annular chamber E around the core parts I|,-2l, the chamber E communicating through passages 22 in the core H with the chamber C. A spring 23 in chamber E normally urges the movable core I! upward against rod l6.

The lower end portion of piston 15 is provided with an annular chamber B which communicates through passages [5a in the piston with the upper chamber A. A compression spring 24 in the chamber B normally urges the piston l5 up ward to counterbalance the effect of gravity on the piston.-

In the normal condition of the apparatus, the solenoid I8 is deenergized and the piston 15 is held in its uppermost position, in which head 14' engages plug 7, by the combined action of springs 23 and 24, the spring 23 acting through core l-l against the lower end of rod 13. In this position of the parts, the volume of chamber A is considerably smaller than shown since the piston I5 is raised from the ring 20, and the volume of chamber C is considerably smaller than shown because the movable core I! is raised from the fixed core 2 I. The chamber A, passages 15a, chamber B, and the space directly under they raised piston l5 are filled with oil. Similarly, the chamber C, passages 22, chamber E, aperture-Rand the space directly under the raised core I! are filled with oil.

In operation, the cylinder l-la is accelerated upwardly, as seen in Figure 1. The integrator becomes subject to that acceleration by virtue of being mounted, for example, in a bombing airplane. When so mounted the integrator functions as an element in toss bombing and may be used in a method of bombing such as disclosed in an application for patent of Harold S. Morton, for Bombing Method, filed June 1, 1944, Serial No. 538,311. That use will occur when the attacking airplane is made to pull up sharply as a preliminary to the release of a bomb, whereupon desiring to integrate the upward acceleration of the airplane the solenoid I8 is energized by the closure of the operating circuit G to lower the which circuit is to close a bomb release circuit F. From this it will be understood that the piston becomes instrumental in delaying the release of the bomb during the acceleration of the airplane until the proper bomb velocity has been reached. The rate of flow of. oil through the orifices 15a will be proportional to the acceleration and the total flow quantity will be propor- 4 a passage therethrough, the piston being movable in the cylinder to displace said fluid through said passage in response to acceleration of the cylinder, means normally securing the piston against movement in the cylinder, means-for releasing said last means and thereby to establish the beginning of a time interval, and means operable by the piston for establishing the end of said time interval. p

2. In a device for obtaining the time integral of acceleration perpendicular to the line of flight of a bombing aircraft preliminarily to the release tional to the integral of the acceleration. It will be apparent that as the accelerationis in-' creased, the time interval from energization of solenoid 18 to closing of contact l46a will be decreaseddueto the greater force of setback on piston I5 and therefore its faster downward movementthrough the oil. Adjustment of the stop plug 1 will vary the starting point of the piston 15 and consequently the stroke of the pistonassembly, as required; In other words, the: result of theintegration is torelease a bomb when the upward velocity of the airplane has changed by an amountset by the movable, contact l4. Provision of the spring 24 to support part of the weight of the piston. [-53 allows the integration of a function of the form a(K b). where a and b are constants and K is the acceleration of the mechanism. In the formula stated, a equals mass, K equals acceleration of the airplane, b equals the counterforce exercised by the spring. Briefly applying this formula, the

velocity of the piston [5 in the cylinder l depends on the force exerted on the oil by the piston. This function is a function of the mass 'andthe accelerating forcegon it. Therefore, the force exerted by the piston isproportional to the product of the mass and accelerating force. The value of the-accelerating force is K minus D. From this it is seen that the total accelerating force is K minus b plus the total force by the piston'cn the oil, in other words a(K -11) Packing at '28 preventspassage of oil above this point while maintaining at constant volume; the chambers into which oil ispermitted to flow, irrespective of the position of the plug 1.

It will be understood, of course, that the apparatus shown will be maintained at ;a constant temperature during use to eliminate viscosity variation in the oil used.

Ifhe acceleration integrator is automatically reset upon deenergizing of the solenoid [8. At that time, the springs 23- and 24 return the parts to their. initial positions, with the head M' engagingplug l, and with the core I! engaging rod [3. During this return movement, the oil is displaced by a reversal of the flow previously described.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. Ina device for obtaining thetime integral of acceleration perpendicular to the line of flight of a bombing aircraft preliminarily to the release of a bomb therefrom, a cylinder containing a hydraulic fluid, apiston in the cylinderhaving jof a bomb therefrom, a cylinder containing a hydraulic fluid, a piston in the cylinder having a passage therethrough, the piston being movable in the cylinder to displace said fluid through said passage in response to acceleration of the cylinder, spring-pressed means normally securing the piston against movement in the cylinder, electromagnetic means for rendering said last means inoperative to secure the piston and thereby establish the beginning of a time interval, and contact means operable by the piston for establishing the end of said time interval.

3. In a device for obtaining the time integral of acceleration perpendicular to the line of flight of a bombing aircraft preliminarily to the release of a bomb therefrom, sacylinder containing a hydraulic fluid, a piston in the cylinderhaving a passage therethrough, a ring in the cylinder intermediate its ends, a spring seated on the ring and normally urging the piston away from the ringthe piston being movable toward the ring against the spring to displace said fluid through said passage in response to acceleration of the cylinder in the direction of thrust of the spring against the piston, a rod on the piston having a contacthead, a stop against which said head is urged by the spring and adjustable to vary the normal position of the piston, asolenoid in the cylinder, a fixed core in the solenoid, a movable core in thesolenoid having a recess therethrough, aspringurging the movable core away from the fixed'core and against said rod to supplement the action of said first spring in urging the piston away fromthe ring, the solenoid being operable toimove said movable core toward thefixed core torelease the rodv and establish the beginning of a time interval-,thereby displacing said fluid through saidreces s, and the piston upon release of the rod being movable to displace said fluid through thepiston passage. in response to acceleration of the cylinder, and a fixed contact on the cyl'inder-engageable by said contact head of the rod upon said" movementof the piston, to establish the endIofsaid-time interval. f

4. A- device for obtaining the timejintegral of acceleration perpendicular tothe line of flight of .a' bombing aircraft preliminarily to the release of a bomb therefrom, said device having a'closed cylinder containing a hydraulic fluid, a piston fitting the cylindensaid piston'having a passage therethroug'h and being movable inonedirection by set-back to displace the fluid through the gjpassagein proportion to the accel ration of the ro'r. a. bomb release circuit, being closed'by the piston at the end of its set-back movement.

5. A device for obtaining the time integral of acceleration perpendicular to the line of flight of abombingaircraft preliminarily to the releaseof to the acceleration of the aircraft, means partially Number Name Date counterbalancing the piston against gravity 737,460 oxley r Aug. 25, 1903 thereby making the set-back movement of the 2,237,326 Barry Apr. 8, 1941 piston solely expressive of the value of the ac- 2,283,180 Buchanan May 19, 1942 celeration of the aircraft, and predeterminedly 10 FOREIGN PATENTS spaced electrical contacts for a bomb release circuit, being moved toward each other by said Number Country Da e inertia-operable closer and engaged to close the 45,402 Austria 10, 1911 circuit after a period of acceleration proportioned 193365 Switzerland July 15, 1933 to the spacing of the contacts. 15 602,524 France 28, 1925 5 a bomb therefrom, said device having a closed REFERENCES CITED cylinder containing a hydraulic fluid, an inertia- The following references are of record in the operable circuit closer including a piston fitting file of this patent:

the cylinder and having a passage therethrough for the displacement of the fluid in proportion 5 UNITED STATES PATENTS WILLIAM B. MCLEAN. 

